Color TV display system

Abstract

A self-converging deflection yoke having toroidally-wound vertical deflection coils incorporates a pair of magnetically permeable field formers mounted on either side of the yoke. The field formers shunt a portion of the external field flux to the vicinity of the electron gun assembly where they form a pincushion-shaped field which aids in vertical coma correction. In one embodiment, a yoke comprising planar-wound vertical coils incorporates both coma-correcting rear field formers and a pair of front crossarm assemblies for providing side-pincushion correction. The resultant yoke provides covergence of electron beams free of coma and side-pincushion distortion with reduced sensitivity to transverse motion. In another embodiment, similar results are obtained without the front crossarms by vertical deflection coil having a nonradial winding configuration.

What is claimed is: 
     
       1. In a television display system having a kinescope including a neck and an electron gun assembly therein for producing three electron beams, and a deflection yoke comprising a deflection coil toroidally wound about a magnetically permeable core encircling the paths of said beams departing said electron gun assembly, said coil producing a delfection field within the region bounded by the interior of said core and an external field; a magnetic field influencing apparatus comprising: first and second magnetically permeable members respectively disposed on opposite sides of said yoke, each of said members having a first end disposed within said external field and a second end disposed at the rear of the entrance end of said deflection yoke and adjacent the neck of said kinescope, each of said members channeling a portion of said external field to its second end, each of said second ends being shaped in such manner as to form a pincushion-shaped field within said kinescope neck in the vicinity of said entrance end of said deflection yoke of such a magnitude and extent as to substantially correct coma errors otherwise introduced by said deflection field.   
     
     
       2. The arrangement defined in claim 1, wherein said second end of each of said magnetically permeable members defines an upper and lower arm disposed substantially perpendicular to said kinescope neck. 
     
     
       3. The arrangement defined in claim 1 wherein said first end of each of said magnetically permeable members is disposed adjacent said core for channeling a portion of the flux in said core into said permeable member. 
     
     
       4. The arrangement defined in claim 1 wherein said toroidally-wound deflection coil effects vertical deflection of said beams, and wherein said deflection yoke additionally includes a saddle-wound deflection coil for effecting horizontal deflection of said beams. 
     
     
       5. The arrangement defined in claim 4 wherein said vertical deflection coil comprises substantially radial windings and wherein said deflection yoke incorporates a pair of crossarm members disposed on either side of said yoke near the front of said yoke for producing a pincushion field in the vicinity of the front of said yoke for correcting side-pincushion distortion. 
     
     
       6. The arrangement defined in claim 4 wherein said vertical deflection coil comprises nonradial windings configured in a manner effecting correction of side-pincushion distortion. 
     
     
       7. In a television display system having a kinescope including a neck and an electron gun assembly therein for producing three electron beams, and a deflection yoke comprising a deflection coil toroidally wound about a magnetically permeable core encircling the paths of said beams departing said electron gun assembly, said coil producing a deflection field within the region bounded by the interior of said core and an external field; a magnetic field influencing apparatus comprising: first and second magnetically permeable members respectively disposed on opposite sides of said yoke, each of said members having a first end disposed within said external field and a second end disposed at the rear of the entrance end of said deflection yoke and adjacent the neck of said kinescope, each of said members channeling a portion of said external field to its second end, each of said second ends being shaped in such manner as to form an upper and lower arm in order to form a pincushion-shaped field within said kinescope neck in the vicinity of said entrance end of said deflection yoke of such a magnitude and extent as to substantially correct coma errors otherwise introduced by said deflection field.